Contribution to the Elongational Viscosimetry of High-Polymeric Solutions

Abstract

Elongational flows play a decisive role in many shaping processes of manufacturing technology. Specific flow phenomena, by which we mean a multitude of instabilities and breaks, may definitely limit the technological possibility of controlling elongation flows, above all in the spinning of artificial fibres, the coating of film materials, and film blowing, In these processes, the rheological characterization of the behaviour of the fluid materials to be processed under elongational load is an indispensable precondition. Work on these problems is carried out in order to define the material function of elongational flow by analogy with simple shear, and to ensure exact measurement in suitable rheometer flows. At present, the rheological characterization of the elongational behaviour of highpolymeric solutions presents difficulties greater than those found in other groups of materials.